Under body cleaning and salt/chemical protection

[Bowruss]

Helllo all.

It's coming round again so I'm thinking about a routine for keeping my under body clean.  I  have no after market stuff on and it's as it left the factory. 

I've  heard cautionary tales about power washing and hose, etc damage so I just need to keep it washed off every say month when they bring out the road chemicals.

Anybody got their own experiences? 

I'm  not really up to a lot of bending to get under the car and I think car wash guys usually couple the under spray jets with those killer brushes.

Anyway, what do you all do if anything?

[TonyHSD]

Hi, 

the best way I found for myself is to wash with hose and water or jet spray with suitable attachments., just spray from a safe distance.
You can use tfr or Snow Foam or one after the other, or simply just pure water. 
Another good idea is to drive on motorways when is heaven rain spring time after the salt been cleaned away. 
And last but not least, best to never use any corrosion protection applied, these are nothing but trouble and can also invalidate your warranty. 👍

[Bowruss]

Thanks Tony.  I'll  see how I go on with mains pressure and a wand thing that will give an aim underneath due to its flexible nozzle end.  

I worry that my Karcher may be too powerful except  on the  less power setting as I can't  see the various connections that could be disturbed by a too powerful jet.

Good point about  the after market coatings.  They are seductive and well  promoted. 

[oldcodger]

Our Nilfisk pressure washer has a car kit that contains 2 special nozzles, both producing lower pressure, one for normal bodywork paint and one thats got an angled head for doing under the car without having to bend right down.

Do Karcher do a similar thing or  if a third party do such fittings ?

[Basil-BarryC]

2 hours ago, oldcodger said:

Our Nilfisk pressure washer has a car kit that contains 2 special nozzles, both producing lower pressure, one for normal bodywork paint and one thats got an angled head for doing under the car without having to bend right down.

Do Karcher do a similar thing or  if a third party do such fittings ?

I seem to remember Karcher did manufacture an accessory for under car cleaning which fitted most Karcher power washers. IIRC Search for Karcher UnderChassis Cleaner 

[AisinW]

For UK and most part of western europe, the snow is mild. Pressure washing the underbody in a car wash is the best and cheapest way to keep it rust free. £1 for 2 minutes of pressure washing is enough after snowy days with salts on the roads.

If you have severe salt application issues, like in the northern part of Scotland, you can apply fat-base spray. It works well and does not trap moisture, unlike heavy rubberized coatings.  Lanolin/wool wax base is easy to apply and safe to rubber and joints. You can get it from Cosmoline, Woolwax, Fluid Film spray.

The rubberized heavy coating is only good when the car was new but not for a used car that has already some dings and surface rust.  If you apply heavy coating on already rusted surface, it will only accelerate the rust tremendously.

[JasonM]

During the summer when the car is dry and clean I’ve used a light mist of Bilt Hamber Dynax UC on bare and painted metal around the sub frames and suspension.  Just avoid getting it near the brake discs.   I doubts it lasts for years but keeps the salt at bay for a winter.   

https://www.parkers.co.uk/car-advice/car-care/best-underseal/

[Chainbreaker]

On 11/10/2024 at 10:12 PM, AisinW said:

For UK and most part of western europe, the snow is mild. Pressure washing the underbody in a car wash is the best and cheapest way to keep it rust free. £1 for 2 minutes of pressure washing is enough after snowy days with salts on the roads.

If you have severe salt application issues, like in the northern part of Scotland, you can apply fat-base spray. It works well and does not trap moisture, unlike heavy rubberized coatings.  Lanolin/wool wax base is easy to apply and safe to rubber and joints. You can get it from Cosmoline, Woolwax, Fluid Film spray.

The rubberized heavy coating is only good when the car was new but not for a used car that has already some dings and surface rust.  If you apply heavy coating on already rusted surface, it will only accelerate the rust tremendously.

Fat based sprays such as lanoguard etc are crap. Very messy to apply, don't last and do nothing to prevent rust spreading.

You're much better off with bit hamber dynax UC as JasonM has mentioned above. It's a lot easier to apply, dries clear so you don't even know it's there and has corrosion inhibitors so actually prevents rust spreading rather than hiding it.

I apply it once a year. Also in winter when there's a lot of salt on the roads (the joys of being in Scotland!) I Snow Foam the underside of the car with built hamber touchless (a Snow Foam that also contains corrosion inhibitors) to get the salt off when doing my regular wash with the car.

 

[AisinW]

@Chainbreaker thanks for the information. the clear coat only work if it has no rust yet. The fat spray is better for old used cars with some surface rust already there. dynac UC is great hard wax

[TonyHSD]

The worst thing to any car is to add undercarriage rust protection of any kind and paint work protection, either fancy called “ ceramic coatings” or wrapping the car in any clear or colourful protection film. 
Every car has already applied in factories top lacquer for the paintwork and under body seal.
Owners only needs to read their book and do regular car washes and spray  underneath  with water. Engine bay wash after salty winters are also a good idea. The car will last the longest, no warning problems too. 
For paintwork a simple wax once 6-12 months with quality brand car wax is the best and easiest way to protect the car. 
 

[Saxmaniac]

I've been through the whole spectrum of rustproofing products over the years and found that virtually all wax based products eventually dry out, rust continues happily underneath. Waxoyl is by far the worst. The thing with lanolin based products is that they are messy and need reapplying yearly but appear to protect very well on new or old metal. They don't form a skin that allows moisture to get trapped underneath and accelerate rust. I have a 20 year old vauxhall that I've used as an informal testbed and now regularly scrape off dried out dinitrol wax that's doing just that, then blast fluid film over. With hindsight I'd just keep applying lanolin products yearly and nothing else 

[AisinW]

On 11/14/2024 at 1:17 PM, TonyHSD said:

The worst thing to any car is to add undercarriage rust protection of any kind and paint work protection, either fancy called “ ceramic coatings” or wrapping the car in any clear or colourful protection film. 
Every car has already applied in factories top lacquer for the paintwork and under body seal.
Owners only needs to read their book and do regular car washes and spray  underneath  with water. Engine bay wash after salty winters are also a good idea. The car will last the longest, no warning problems too. 
For paintwork a simple wax once 6-12 months with quality brand car wax is the best and easiest way to protect the car. 
 

That is exactly what I do. Just pressure washer the underbody with pressure wash shop, £1 is enough for 2-3 minutes good high pressure underbody wash. If you live in high snowy area like Nordic or gulag places then underbody spray makes sense.